1. Field of the Invention
The present invention relates to reducing power consumption of an electronic apparatus, and more particularly, to an electronic apparatus having a signal processing circuit selectively entering a power saving mode according to operation status of a receiver logic implemented for processing satellite signals from a global navigation satellite system and related method thereof.
2. Description of the Related Art
GPS receivers are widely used in a variety of fields. For example, a navigation device has a GPS receiver included therein for providing needed positioning information to perform the navigation function. In general, the conventional navigation device has two processors, one implemented in the GPS receiver for baseband signal processing, and the other implemented in a navigation host to process positioning information provided from the GPS receiver for navigation purpose. After the integrated navigation device is powered on, the baseband processor in the GPS receiver and the navigation processor in the navigation host are both running in full power for performing respective intended functions. It is possible that the GPS receiver is unable to generate the required positioning information during a period of time. For example, the GPS receiver requires a period of time to search for satellites available on the sky and then fix the location according to satellite signals generated from the tracked satellites after a cold start. In other words, the GPS receiver can't obtain the required positioning information immediately after the cold start. Additionally, when the signal quality of the received satellite signals is low or there are insufficient satellites in sight, the GPS receiver is unable to obtain the positioning information successfully. Under these circumstances, the navigation processor however still runs in full power and consumes much power even though the positioning information is temporarily unavailable. Additionally, in certain applications, the navigation function is not active all the time. However, the conventional GPS receiver, integrated into the navigation device, outputs the computed position information to the navigation host continuously, if the position information can be obtained successfully. As a result, the overall power consumption is inevitably increased due to redundant data transmission of the position information between the GPS receiver and the navigation host.